Viruses of the Parvoviridae family are small non-enveloped icosahedral capsid viruses characterized by a single stranded DNA genome. Parvoviridae family viruses consist of two subfamilies: Parvovirinae, which infect vertebrates, and Densovirinae, which infect invertebrates.
Viruses of the Parvoviridae family are used as biological tools due to a relatively simple structure that may be easily manipulated with standard molecular biology techniques. The genome of the virus may be modified to contain a minimum of components for the assembly of a functional recombinant virus, or viral vector, which is loaded with or engineered to express or deliver a desired nucleic acid construct, e.g., a transgene, polypeptide-encoding polynucleotide or modulatory nucleic acid, which may be delivered to a target cell, tissue or organism.
Parvoviridae viral vectors are adaptable to the delivery of a wide range of nucleic acid constructs and are therefore often produced in the laboratory in small volumes with a variable concentration of viral particles. It is well understood, however, that viral vector production for larger scale clinical trials and commercialization using current cell production systems can be cost and time prohibitive. According to U.S. Pat. No. 6,723,551, a typical clinical study may require the production of more than 1015 viral vector particles. At a production rate of 10,000 viral vector particles per cell, transfection and culture of approximately 1011 cells would require the equivalent of 5,000 175-cm2 flasks of cells without taking into account loss of yield during the purification process. In addition, producing viral vectors for clinical use requires purification strategies to eliminate contaminants that may be present in a viral replication cell.
In view of these and other issues there remains a need for alternative and improved methods for efficiently, safely, and economically producing a large amount of viral vectors. The present invention provides compositions and methods for the improved production of viral vectors, e.g., parvoviral vectors, and consequently more efficacious therapeutic modalities.